1. Technical Field
The present invention is directed generally to the production of knock-in non-human mammals and cells and chimeric immunoglobulin chains and antibodies.
2. Description of the Related Art
Disease therapies utilizing monoclonal antibodies (mAbs) have revolutionized medicine, and mAb-based drugs are now utilized in the treatment of cancer, autoimmunity, inflammation, macular degeneration, infections, etc. However, the available technologies for generation and discovery of mAbs for use in the prevention and treatment of diseases and disorders have significant drawbacks including inefficiency, absence or loss of sufficient potency, absence or loss of specificity and the induction of an immune response against the therapeutic mAb. The first attempts to use mAbs as therapeutics were hindered by the immunogenicity of the mouse amino acid composition of the mAbs. When administered to humans, the mouse amino acid sequence elicited a human anti-mouse antibody (HAMA) response that dramatically reduced the potency and pharmacokinetics of the drug as well as causing severe and potentially fatal allergic reactions.
Additional methods to generate mAb therapeutics include chimerized mAbs (cmAbs) created through recombinant DNA technology combining a mouse-derived variable domain appended to a human constant region. Other methods of generating antibodies involve humanizing mAbs in vitro to further reduce the amount of mouse amino acid sequence in a therapeutic mAb. Antibody-display technologies developed to generate “fully-human” antibodies in vitro have yet to adequately mimic the natural antibody maturation process that occurs during an in vivo immune response (see pg. 1122-23, Lonberg, Nat. Biotech. (2005) 23:1117-1125.) mAbs developed using these methods can elicit an immune response that can reduce efficacy and/or be life-threatening, and they are typically a time-consuming and costly process. Also, during the molecular processes inherent in these methods, loss of affinity and epitope shifting can occur, thereby reducing potency and introducing undesirable changes in specificity.
Transgenic mice have been engineered to produce fully human antibodies by introducing human antibody transgenes to functionally replace inactivated mouse immunoglobulin (Ig) loci. However, many of these transgenic mouse models lack important components in the antibody development process, such as sufficient diversity in the genes from which antibody variable regions are generated, the ability to make IgD (Loset et al., J. Immunol., (2004) 172:2925-2934), important cis regulatory elements important for class switch recombination (CSR), or a fully functional 3′ locus control region (LCR) (e.g., U.S. Pat. No. 7,049,426; and Pan et al., Eur. J. Immunol. (2000) 30:1019-1029). Some transgenic mice contain yeast artificial chromosomes or human miniloci as integrated transgenes. Others carry transchromosomes that exhibit various frequencies of mitotic and meiotic instability. Furthermore, the fully human constant regions of these transgenic mice function sub-optimally due to reduced activity in conjunction with other endogenous and trans-acting components of the BCR signal transduction apparatus, e.g., Igα and Igβ, and Fc receptors (FcR), as compared to normal mice.
Mice have also been genetically engineered to produce chimeric antibodies that are composed of human V domains appended to mouse C domains that remain fully intact, with the fully-intact and modified portions including all genomic DNA downstream of the J gene cluster (see U.S. Pat. Nos. 5,770,429 and 6,596,541 and U.S. Patent Application Publication No. 2007/0061900). Human V regions from these mice can be recovered and appended to human constant region genes by molecular biological methods and expressed by recombinant methods to produce fully-human antibodies. The antibodies from these mice may exhibit reduction or loss of activity, potency, solubility etc. when the human V region is removed from the context of the mouse C domains with which it was evolved and then appended to a human C region to make a fully human antibody.
Current methods of developing a therapeutic mAb can alter functions of the antibody, such as solubility, potency and antigen specificity, which were selected for during initial stages development. In addition, mAbs generated by current methods have the potential to elicit a dangerous immune response upon administration. Current human and chimeric antibody producing mice lack appropriate genetic content to function properly, e.g., genetic diversity, cis regulatory elements, trans acting regulatory elements, signaling domains, genetic stability. It would be beneficial to develop methods and compositions for the enhanced generation and discovery of therapeutic antibodies and that retain potency and specificity through the antibody generation, discovery, development, and production process without eliciting an immune response, as well as methods of producing such antibodies. The present invention provides a solution for generating such antibodies in transgenic animals.